WATER HYGIENE AND SAFETY
was to apply an injection disinfection to the distribution lines of the ward. This was achieved by applying 100 ppm of Hydrogen Peroxide with a two-hour contact time. The aim was to target potential biofilm that appeared to be present on the ward’s water system. The post-disinfection laboratory results showed no real change in Legionella levels. We did, however, start to notice patterns emerging. The first, obvious and interesting fact was that the Legionella species, confirmed by MALDI-ToF5 UKAS-accredited3
at a laboratory, was nearly
always Legionella anisa (L. anisa). This pattern was compared with Lakeside Water’s records of 13,500 previous laboratory results for Legionella over a 33-month period (from January 2019). The same pattern was observed. Given that Legionella was still prominent
in the system, a second disinfection was undertaken a month later. This time all the strainers were removed and disinfected, independently. The system was then disinfected minus the strainers. The biocide of choice was again Hydrogen Peroxide, with the aim of targeting all the remaining biofilm. All strainers were re-installed post disinfection.
Positive sample results continued Three days were allowed to pass, and all the strainers were again removed, cleaned, and disinfected. This was done in case any biofilm had sheared off post- the disinfection and become trapped in the strainers. Samples were taken again after two days following completion of all disinfection works through systems and strainers from the ward distribution system. Positive results kept coming, resulting in more investigation of the wider systems. It was noted that around 15 years ago the ward had been refurbished, and that while the central distribution remained the original copper, all the local drop-downs to this ward were installed with plastic pipework with crimped fittings. Further research identified that these components, at the time of installation, were predominantly used for underfloor heating pipework; the type of piping now common on cruise ships with WRAS6
approval since
2016. To compound matters, there was no insulation of the pipework post- the main centralised copper distribution network. This allowed for heat transfer, and is clearly a major problem. A group discussion was held on the
best way forward given the scenario, and involved the Lakeside Water senior Contract manager, two Authorising Engineers, Lakeside Water’s client, its tenant, and associated Infection Control teams. It was agreed via a ‘Teams’ meeting that a change of chemical be implemented to see if bacteria in this specific area had built up a tolerance to Hydrogen Peroxide and the ‘shock’ of a new chemical might
50000 45000 40000 35000 30000 25000 20000 15000 10000 5000 0
help. Chlorine was to be applied to the system at 100 ppm for a one-hour contact time to see if it would impact the Legionella counts. Sadly it did not.
Letting the system ‘settle down’ Given that the system had undergone disinfections for three consecutive months, it was decided that it required a month of no treatment to allow it to ‘settle down’. At this time (December 2020) discussions were taking place to see if this would become a live COVID ward. This would have a direct impact on access to the area, root cause analysis, and risk mitigation works. It was decided to install a permanent Chlorine Dioxide dosing unit to the hot and cold water storage tanks to aid risk mitigation; however, these were 25 metres in the air, and in a confined space. The decision was thus made to move the tanks, as had originally been planned prior to the calorifier issues, and this, compounded by the ongoing plumbing challenges, resulted in a decision to upgrade the associated plant and equipment.
Second injection of ward and
New Cals installed
strainer strip-outs – hydrogen peroxide
The upgrade, completed in January
2021, consisted of two new GRP tanks, two brand new booster pump arrangements, installation of a continuous Chlorine Dioxide dosing unit, and relocation of the water softener and its upgrading from a Simplex to a Duplex unit. Throughout this entire period, every
asset across the whole hospital was being flushed twice a week; with every outlet on the ‘problem ward’ being flushed for a minimum of five minutes every day. Lakeside Water subsequently installed T-safe 92-day Lamina Flow tap filters and T-safe Medical Shower Filters to all assets within the ward to protect patients from waterborne pathogens. Monthly sampling, both pre- and post-flush on all outlets, was planned and executed over this time in line with the Water Safety Plan. The ongoing positive results (pre-filtration) on the ward, with significant bacterial counts, left the Infection Control teams with concerns over staff and patient welfare. To provide assurance to Infection Control teams that immediate risk mitigation was effective in protecting patients, staff, and visitors to
Figure 3a: post-flush bacterial data trend.
New tanks and booster system installed, new chlorine dioxide system in use
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Post flush
Anisa count SG1 count SG2-15 count
Spp count (not anisa)
Post
Post
Post
Post Feb 20 Mar 20 May 20 Jun 20
Post Jul 20
Post
Post
Post Nov 20 Dec 20 Feb 21
Post Mar 21
Post Apr 21
Post May 21
Post Jun 21
Post Aug 21
Post Sep 21
Post Oct 21
Cylinders fixed, new thermostat installed to CAL 1, new destrat pumps installed to CAL 1 and CAL 3, daily flushing, pasteurisation
Injection Disinfection of Ward – Hydrogen Peroxide
Cylinders fixed, new thermostat installed to CAL 1, new destrat pumps installed to CAL 1 and CAL 3, daily flushing, pasteurisation – FEB 2020
New Cals installed – MARCH 2020
3rd Injection Disinfection of Ward – Chlorine
Pre Flush
3rd Injection Disinfection of Ward – Chlorine
Clo2
dosing increased
Removal of plastic pipework and replace with copper
Figure 3b: pre-flush bacterial data trend.
Anisa count SG1 count SG2-15 count
Spp count (not anisa)
Pre Jun 20
Pre Jul 20
Pre Nov 20
Pre Dec 20
Pre Feb 21
Pre Mar 21
Pre Apr 21
Pre May 21
Pre Jun 21
Pre Aug 21
Pre Sep 21
Pre Oct 21
Injection Disinfection of Ward – Hydrogen Peroxide
Second injection of ward and strainer strip- outs – hydrogen peroxide
New tanks and booster system installed, new chlorine dioxide system in use
Clo2
dosing increased
Removal of
plastic pipework and replace with copper
March 2022 Health Estate Journal 23
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